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Mayfly Watch Results

River-wide observations of mayflies along the Upper Mississippi River began in 2012. The number of citizen scientist volunteers contributing to this effort has been increasing each year. 

Graph created by Mark Steingraeber, FWS

To date, mayfly emergence events have been reported at sites in four states scattered along a more than 400-mile reach of the Upper Mississippi River spanning 19 navigation pools. On the maps below, emergence locations are shown for 2012, 2013, and 2014. Small yellow circles represent locations (i.e., navigation pools) of reported emergence events.  Large yellow circles show the total number of navigation pools where emergence events were reported each year. 

Maps created by Mark Steingraeber, FWS

The maps below show locations where the annual relative abundance of emergent mayflies had an emergence strength ranging from moderate to very heavy (i.e., values > 3) on the five-point Johnson Emergence Scale in 2012, 2013, and 2014. Small orange circles represent the locations (i.e., navigation pools) of reported emergence events. The pie charts show the percent of these navigation pools with emergence events that ranged from moderate to very heavy each year. 

Map created by Mark Steingraeber, FWS

The calendar below shows annual (2012-14) dates of the peak in synchronous emergence for Hexagenia bilineata mayflies from navigation pools in the Upper Mississippi River.   The annual timing of the emergence peak can vary from year to year, due in part to cumulative differences in daily river water temperatures from one year to another.

Calendar created by Mark Steingraeber, FWS

Reports of annual mayfly emergence events from navigation pools of the Upper Mississippi River are providing information needed by scientists to validate the accuracy and precision of a laboratory-derived thermal model that may predict when a mass emergence will occur based on daily river water temperatures. The maps below show the locations where mayfly thermal development was modeled (left) and where the model was validated (right) in recent years.  Small pink circles on the maps (below left) represent each location (i.e., navigation pool) wheremayfly thermal development was modeled and the large pink circles show the annual totalnumber of these locations. Small white circles on the maps (below right) represent eachlocation (i.e., navigation pool) where the reported date of peak mayfly emergence fell within the range of dates predicted by the thermal model and the pie charts show the percent of these sites where the models were validated. 

Maps created by Mark Steingraeber, FWS